New Mexico's Pet Resource


Anterior Cruciate Ligament Surgery

By Nancy Marano

Amber, Meggie, and Jojo have never met, but they are soulmates. All are older dogs, ranging in age from 11 to 14 years, all experienced lameness due to a torn anterior cruciate ligament in the stifle joint (canine for knee) and all underwent successful surgery for the problem.

Amber, a 14-year-old Golden Retriever living in British Columbia, loved hiking the trails around her home with her owner. Then her back left leg started giving out on her. She was in considerable pain and could no longer walk. Her owner, Diane Mortensen, took her to the veterinarian, who found that Amber’s anterior cruciate ligament was torn. Since surgery in an elderly pet always carries extra risk, Diane sought a specialist to perform the surgery. Now, more than a year later, she is back hiking the trails with her owner and enjoying life with her friends.

Meggie, a 12-year-old Welsh Corgi from Albuquerque, New Mexico, could not walk without significant pain. She too had a torn anterior cruciate ligament. Following the surgery she is pain-free and back to her normal routine.

Jojo, an 11-year-old, overweight Yorkshire Terrier, tore his anterior cruciate ligament when he jumped from a window ledge during an attempt to catch a squirrel. He is still recovering, but his prognosis is excellent.


The stifle joint in a dog is similar to the human knee. Within it are the femur, tibia, patella(kneecap) bones, the medial and lateral collateral ligaments, which run on either side of the joint, and the cranial and caudal cruciate ligaments, which cross inside the joint. There are also menisci that act as shock absorbers between the bones and perform the duties of cartilaginous ligaments.

Unlike the hip, which is a ball-and-socket joint, the stifle is an articulated joint where the femur (thigh bone), fibula, and the tibia (shin bone) meet and are held together by the ligaments. The function of the cruciates is to stabilize the joint. They limit the internal rotation and movement of the tibia and help prevent the joint’s hyperextension.

“If any of those five ligaments is broken, the joint becomes unstable,” said Dr. Michael Riegger, D.V.M. and Diplomate, American Board of Veterinary Practitioners. “When it becomes unstable, the internal movement chews up the joint and arthritis sets in.”


Injury to the anterior cruciate ligament (ACL), also known as the cranial cruciate ligament (CCL), is the most common cause of hind-limb lameness. Such an injury can result from trauma, poor conformation, obesity or degenerative joint disease.

Traumatic injury usually occurs in younger dogs and is tied to a specific traumatic event. The more usual cause of the problem is chronic degeneration of the joint through the wear and tear of the aging process. It is much more likely this injury will he found in older dogs, aged seven years and up. It is also true that a ligament weakened by degenerative disease is more easily ruptured.

If the ligament ruptures, the body makes an effort to heal it. For a while the dog will seem to get better, but then the lameness will return. This is usually the result of damage to the meniscus or the total rupture of an already torn ligament.

When lameness, with accompanying pain, occurs, the veterinarian performs a cranial drawer test on the affected limb. This test is done by placing the fingers on either side of the affected joint. If movement or instability can be detected within the joint during palpation, it is a sure indication the joint is damaged. Often, this test must he done while the dog is sedated because of the pain and the dog’s tendency to guard an injury. This is particularly true when testing a larger dog. The veterinarian will follow up with x-rays to determine the extent of the problem.


Several factors must be taken into consideration in determining treatment. What is the dog’s age and general physical condition? What is the dog’s lifestyle? Is he a working dog or does he lead a sedentary life? What about the economic considerations? These might be a factor since this surgery costs from $250-800. How conscientiously will the owner follow post-operative care instructions?

Conservative treatment consists of strict confinement, hut no surgery. This may help some dogs, especially those weighing under 30 pounds. Most veterinarians, though, prefer to stabilize the joint via surgery to lessen further de generative joint disease. This also lessens the likelihood that the other stifle will be damaged, some thing that commonly occurs because of the extra strain put on the healthy joint to compensate for the painful one.

Many surgical procedures are available to stabilize the joint. All of these procedures give good results and none has been demonstrated to be overwhelmingly superior to the others. Dr. Riegger’s favorite technique is called fibular transposition. “I take the fibula and the lateral collateral ligament and move them. Ordinarily, the orientation of the ligament is straight up and down. By moving the fibula and the lateral collateral ligament forward, we change the orientation of the head of the fibula and the ligament to do the work of two,” he said. “Instead of having five ligaments stabilize the joint, we now have four.”

If the ligament were severely weakened, he would not use this procedure. Then he would choose an imbrication technique in which a suture is passed through the connective tissue and then tightened to prevent rotation within the joint. Essentially it forms an additional ligament.

All remnants of the broken ligament and any pieces of damaged cartilage or meniscal tissue are cleaned out of the joint before the procedure to repair the ligament is done.


No matter which procedure is used to stabilize the joint, the results of this surgery are quite successful. Between 85%-95% of the patients regain good to excellent function in their limb.

Depending on the type of procedure performed, and the surgeon’s preference, the dog may leave with no bandage or with a Robert Jones bandage, which is a soft cast that immobilizes the joint to some degree. The dog’s activities are very restricted the first week following surgery. The dog is confined and allowed outside on a leash for eliminations only. Gradual resumption of normal activity over a six to twelve week period is the standard.

Dr. Riegger says, ”For one week, the dog gets to sit around and watch Oprah! Over the next six to seven weeks, it returns to its normal life pattern. We do check-ups at one, two, four, and eight weeks. Usually the recovery rate at these visits is 25%, 50%, 75%, perfect. 95% of the dogs regain 95% use of their leg within eight weeks.”

Amber and Jojo both left the hospital with soft bandages. Meggie didn’t need a bandage, but she wore an Elizabethan collar to discourage her from chewing on the wound. Amber suffered depression during her recovery because she is a very social dog and missed her contacts with people. This has passed now that she has regained her strength and ability to move around. Owners are urged to do range-of-motion exercises with the dog during recovery to help strengthen the joint and muscles. This is particularly true with larger dogs.

The best reward for doing this surgery is seeing a dog that was lame and in constant pain again running, playing, and hiking without difficulty.


Dr. Michael Riegger, D.V.M., Diplomate, American Board of Veterinary Practitioners, Northwest Animal Clinic Hospital & Specialty Practice, 1000 Alameda Blvd. NW Albuquerque, NM 87114.

Dr. Rick Snook, D.V.M., Arrighetti Animal Hospital, Santa Fe, NM. 505/471-2888.

Bojrab, M. Joseph, ed. Current Techniques in Small Animal Surgery. 3rd edition. Philadelphia: Lea & Febiger, 1990.

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